Methyl-n-propyl tetrahaloterephthalates



Patented Sept. 12, 1967 3,341,571 METHYL-N-PROPYL TETRAHALO-TEREPHTHALATES Sidney B. Richter, Chicago, and Alfred A. Levin, Skokie,

11]., assignors to Velsicol Chemical Corporation, Chicago, 11]., acorporation of Illinois No Drawing. Filed Feb. 23, 1965, Ser. No.434,654 4 Claims. (Cl. 260-475) This invention relates to the productionof new herbicidal compositions of matter. More specifically, thismvention relates to new chemical compounds of the formula wherein X ishalogen. While the halogen can be fluorine, chlorine, bromine, oriodine, the preferred halogen is chlorine or bromine, since the requiredstarting materials are more readily available. A most preferred halogenis chlorine. These new compounds have been found to be useful asherbicides, particularly as herbicides for grassy weeds.

The compounds of the present invention are termed methyl 'n-propyl2,3,5,6-tetrahaloterephthalates. Exemplary of the specific compounds ofthe present invention are: methyl n propyl2,3,5,6-tetrachloroterephthalate, methyl n-propyl2,3,5,6-tetrabromoterephthalate, methyl n-propyl2,3,5,6-tetrafluoroterephthalate, and the like.

The manner in which the compounds of this invention can be prepared isillustrated in the following examples:

EXAMPLE 1 Preparation 4-carb0 meihoxy-2,3,5,6- tetrachlorobcnzoic acidDimethyl 2,3,5,6-tetrachloroterephthalate (65 g.; 0.2 mol), which can beprepared as described by Rabjohn, J.A.C.S., 70, 3518 (1948), dissolvedin dioxane (400 ml.) is placed into a 1 liter, three-necked flaskequipped with a mechanical stirrer, reflux condenser and heating mantle.Potassium hydroxide (10.9 g.; 0.2 mol) in 130 ml. of 3:2dioxane-methanol solution was added to the flask. The mixture was heatedat reflux with stirring for six hours and then poured into one liter ofcold water to precipitate unreacted dimethyl2,3,5,6-tetrachloroterephthalate, which upon extraction from the aqueoussolution with diethyl ether and stripping of the ether yielded 33.8 g.(0.1 mol) of unreacted dimethyl 2,3,5,6-tetrachloroterephthalate. Theaqueous solution was acidified with hydrochloric acid yielding an oil,which was dissolved in diethyl ether. The ethereal solution wasseparated from the aqueous mixture, washed with cold water, dried overmagnesium sulfate, filtered free of drying agent, and stripped ofdiethyl ether by heating in vacuo to yield an oil, which upontrituration with pentane yielded a yellow solid. The solid wasrecrystallized from pentane to yield the half-ester acid melting 1679C., in an 82.7% yield based on recovered starting material. Thehalf-ester acid had the following elemental analysis:

Calculated for C H Cl O Theoretical: C, 34.00%; H, 1.27%. Found: C,34.65%; H, 1.29%.

Infrared spectra of the half-ester acid indicated no dimethylterephthalate was present in the product.

EXAMPLE 2 Preparation of 4-carb0meth0xy-2,3,5,6- tetrachlorobenzoylchloride A mixture of the half-ester acid (8.5 g.; 0.027 mol) preparedin Example 1, and thionyl chloride (50 ml.) was heated at reflux for 16hours. The mixture was then cooled and excess thionyl chloride removedby heating under reduced pressure to yield an oil which solidified onstanding. The solid was triturated with a small amount of pentane toyield crude acyl chloride melting at 824 C. in a 74.4% yield. The crudematerial had the following elemental analysis:

Calculated for C H O Cl Theoretical: C, 32.13%; H, 0.9%. Found: C,33.13%;1-1, 1.28%.

Infrared spectra of the crude material indicated no halfester acid waspresent.

EXAMPLE 3 Preparation of methyl n-propyl 2,3,5,6-tetrachloroterephthalate A mixture of the product of Example 2 (10.8 g.;0.03 mol) and n-propanol ml.) was heated at reflux for 16 hours. Excessn-propanel was removed by warming on a steam bath under reducedpressure. The oily residue was distilled to collect methyl n-propyl2,3,5,6-tetrachloroterephthalate as the fraction boiling at 144 C. at0.2 mm. mercury pressure and having a refractive index at 27 C. of 1.5363 and the following elemental analysis:

Calculated for: C H Cl O Theoretical: C, 40.03%; H, 2.80%. Found: C,40.60%; H, 3.10%.

The other compounds of the present invention can be prepared readily inthe manner of the previous examples by utilizing the appropriatestarting materials. Given in Examples 4 and 5 are the reactants requiredto form the named compound of the present invention.

EXAMPLE 4 Dimethyl 2,3,5,6 tetrabromoterephthalate+potassiumhydroxide+thionyl chloride+n-propanol=methyl n-propyl2,3,5,6-tetrabromoterephthalate.

EXAMPLE 5 Dimethyl 2,3,5,6 tetrafiuoroterephthalate+potassiumhydroxide+thionyl chloride+n-propanol:methyl n-propyl2,3,5,6-tetrafluoroterephthalate.

For practical use as herbicides, the compounds of this invention aregenerally incorporated into herbicidal compositions which comprise aninert carrier and a herbicidally toxic amount of such a compound. Suchherbicidal compositions, which can also be called formulations, enablethe active compound to be applied conveniently to the site of the weedinfestation in any desired quantity. These compositions can be solidssuch as dusts, granules, or Wettable powders; or they can be liquidssuch as solutions, aerosols, or emulsifiable concentrates.

For example, dusts can be prepared by grinding and blending the activecompound with a solid inert carrier such as the tales, clays, silicas,pyrophyllite, and the like. Granular formulations can be prepared byimpregnating the compound, usually dissolved in a suitable solvent, ontoand into granulated carriers such as the attapulgites or thevermiculites, usually of the particle size range of from about 0.3 to1.5 mm. Wettable powders, which can be dispersed in water or oil to anydesired concentration of the active compound, can be prepared byincorporating wetting agents into concentrated dust compositions.

In some cases the active compounds are sufliciently soluble in commonorganic solvents such as kerosene or xylene so that they can be useddirectly as solutions in these solvents. Frequently, solutions ofherbicides can be dispersed under superatmospheric pressure as aerosols.However, preferred liquid herbicidal compositions are emulsifiableconcentrates, which comprise an active compound according to thisinvention and as the inert carrier, a solvent and an emulsifier. Suchemulsifiable concentrates can be extended with water and or oil to anydesired concentration of active compound for application as sprays tothe site of the weed infestation. The emulsifiers most commonly used inthese concentrates are nonionic or mixtures of nonionic with anionicsurface-active agents. With the use of some emulsifier systems aninverted emulsion (water-in-oil) can be prepared for direct applicationto weed infestations.

A typical herbicidal composition according to this invention isillustrated by the following example, in which the quantities are inparts by weight.

EXAMPLE 6 Preparation of a dust Product of Example 3 10 Powdered talc 90The above ingredients are mixed in a mechanical grinder-blender and areground until a homogeneous, free-flowing dust of the desired particlesize is obtained. This dust is suitable for direct application to thesite of the weed infestation.

The compounds of this invention can be applied as herbicides in anymanner recognized by the art. One method for the control of weedscomprises contacting the locus of said weeds with a herbicidalcomposition comprising an inert carrier and as an essential activeingredient, in a quantity which is herbicidally toxic to said weeds, acompound of the present invention. The concentration of the newcompounds of this invention in the herbicidal compositions will varygreatly with the type of formulation and the purpose for which it isdesigned, but generally the herbicidal compositions will comprise fromabout 0.05 to about 95 percent by weight of the active compounds of thisinvention. In a preferred embodiment of this invention, the herbicidalcompositions will comprise from about 5 to about 75 percent by weight ofthe active compound. The compositions can also comprise such additionalsubstances as other pesticides, such as insecticides, nematocides,fungicides, and the like; stabilizers; Spreaders; deactivators;adhesives, stickers, fertilizers, activators, synergists, and the like.

The compounds of the present invention are also useful when combinedwith other herbicides and/or defoliants, dessicauts, growth inhibitors,and the like, in the herbicidal compositions heretofore described. Theseother materials can comprise from about 5% to about 95% of the activeingredients in the herbicidal compositions. Use of combinations of theseother herbicides and/ or defoliants, dessicants, etc., with thecompounds of the present invention provide herbicidal compositions whichare more effective in controlling weeds and often provide resultsunattainable with separate compositions of the individual herbicides.The other herbicides, defoliants, dessicants and plant growthinhibitors, with which the compounds of this invention can be used inthe herbicidal compositions to control weeds, can include chlorophenoxyherbicides such as 2,4-D, 2,4,5-T, MCPA, MCPB, 4(2,4-DB), and the like;carbamate herbicides such as IPC, CIPC, swep, barban, and the like;thiocarbamate and dithiocarbamate herbicides such as CDEC, methamsodium, EPTC, diallate, PEBC, and the like; substituted urea herbicidessuch as dichloral urea, fenuron, monurou, diuron, linuron, neburon, andthe like; symmetrical triazine herbicides such as simazine, chlorazine,atrazine, trietazine, simetone, prometone, propazine, ametryne, and thelike; chloroacetamide herbicides such as alpha- 4chloro-N,N-dirnethylacetamide, CDEA, alpha-chloro-N- isopropylacetamide,4 (chloroacetyl)morpholine, 1 (chloroacetyl)piperidine, and the like;chlorinated aliphatic acid herbicides such 'as TCA, dalapon, 2,3-dichloropropiouic acid, and the like, chlorinated benzoic acid andphenylacetic acid herbicides such as 2,3,6-TBA, 2,3,5,6-TBA, dicamba,tricamba, amiben, fenac, 2-methoxy-3,6-dichloropherrylacetic acid,3-methoxy-2,6-dichlorophenylacetic acid,2-methoxy-3,5,6-trichloropheny1- acetic acid, and the like; and suchcompounds as aminotriazole, maleic hydrazide, phenyl mercuric acetate,endothal, biuret, technical chlordane, diquat, erbon, DNC, DNBP,dichlobenil; DPA, diphenamid, dipropalin, trifluralin, solan, dicryl,merphos, DMPA and the like. Such herbicides can also be used in themethods and compositions of this invention in the form of their salts,esters, amides, and other derivatives whenever applicable to theparticular parent compounds.

Weeds are undesirable plants growing where they are not wanted, havingno economic value, and interfering with the production of cultivatedcrops, with the growing of ornamental plants, or with the welfare oflivestock. Many types of weeds are known, including annuals such aspigweed, lambsquarters, foxtail, crabgrass, wild mustard, fieldpennycress, ryegrass, goose-grass, chickweed, wild oats, velvet leaf,purselane, barnyard grass, and smartweed; biennials such as wild carrot,great burdock, mullein, round-leaved mallow, blue thistle, bull thistle,hounds-tongue, moth mullein, and purple star thistle; or perennials suchas white cockle, perennial ryegrass, quackgrass, Johnson grass, Canadathistle, hedge bindweed, Bermuda grass, sheep sorrel, curly dock,nutgrass, field chickweed, and weeds can be classified as broadleaf orgrassy weedscIt is economically desirable to control the growth of suchweeds without damaging beneficial plants or livestock.

The new compounds of this invention are particularly valuable for weedcontrol because they are toxic to many species and groups of weeds whilethey are relatively nontoxic to many beneficial plants. The exact amountof compound required will depend on a variety of factors, including thehardiness of the particular weed species, weather, type of soil, methodof application, the kind of beneficial plants in the same area, and thelike. Thus, while the application of up to only about one or two ouncesof active compound per acre may be sufficient for good control of alight infestation of weeds growing under adverse conditions, theapplication of ten pounds or more of active compound per acre may berequired for good control of a dense infestation of hardy perennialweeds growing under favorable conditions.

The herbicidal toxicity of the new compounds of this invention can beillustrated by many of the established testing techniques known to theart, such as pre and post-emergence testing. In one pre-emergence test,emulsifiable concentrates or solutions prepared as heretofore.

described can be extended with water or oil or other suitable extenders,to obtain various concentrations of the active compound. Theseconcentrates are sprayed on the surface of soil which had been seededless than twentyfour hours earlier with weed seeds. After spraying thesoil containers are maintained under normal lighting conditions andsupplied with heat as required and daily or more frequent watering.about 7 to about 20 days, and the degree of injury to the Weeds isrecorded. The results indicate that compounds of this invention possessa high order of herbicidal activity.

To demonstrate the post-emergence activity of the compounds of solutionsof various concentrations of the aforementioned active compounds aresprayed on the foliage of weeds that have attained a prescribed size.After spraying, the

winter-cress. Similarly, such The weeds are observed for i thisinvention, emulsifiable concentrates or.

5 6 quently. The Weeds are observed periodically for up to ReferencesCited 14 days or more, and the severity of injury to the Weeds UNITEDSTATES PATENTS 1s recorded. The results indicate that tne compounds ofthis invention possess a high order of herbicidal activity. 2,396,5133/1946 Jones 71 2-6 We Claim: 5 2,557,639 6/1951 Derr et al 260475 1 Acompound of the formula Jones Y X 2,893,855 7/1959 Smith 712.6

ff 1 I ff FOREIGN PATENTS 10 1,265,053 8/1960 France.

I X X LORRAINE A. WEINBERGER, Primary Examiner. Wham X JAMES THOMAS,JR., Examiner.

2. Methyl n-propyl 2,3,5,6-tetrachloroterephthalate. 3. Methyl n-propyl2,3,5,6-tetrabrom0terephthalate. A. I. ADAMCIK, T. L. GALLOWAY, 4.Methyl n-propyl 2,3,5,6-tetrafluoroterephthalate. 15 AssistantExaminers.

1. A COMPOUND OF THE FORMULA